Assessment of the absorption, metabolism and excretion of [14C]pasireotide in healthy volunteers using accelerator mass spectrometry

The position of combined medical treatment in acromegaly

Advances in combination medical treatment have offer new perspectives for acromegaly patients with persistent disease activity despite receiving the available medical monotherapies. The outcomes of combination medical treatment may reflect both additive and synergistic effects. This review focuses on combination medical treatment and its current position in acromegaly, based on clinical studies evaluating the efficacy and safety of combined medical treatment(s) and our own experiences with combination therapy. Arch Endocrinol Metab. 2019;63(6):646-52.

How to Position Pasireotide LAR Treatment in Acromegaly

CONTEXT

Pasireotide long-acting release (LAR) is a somatostatin multireceptor ligand, and in the current consensus criteria pasireotide LAR is considered the second-line medical treatment for acromegaly. We present in this article our recommendations to define the position of pasireotide LAR in the treatment of acromegaly and provide recommendations for the management of pasireotide-induced hyperglycemia.

EVIDENCE ACQUISITION

Our recommendations are based on our experiences with the pasireotide LAR and pegvisomant (PEGV) combination study and the available basic or clinical articles published in peer-reviewed international journals on pasireotide LAR and acromegaly.

EVIDENCE SYNTHESIS

In accordance with the current consensus criteria, we recommend pasireotide LAR monotherapy as a second-line therapy in young patients who show tumor growth during first-generation somatostatin receptor ligand (SRL) therapy and in patients who show tumor growth during PEGV therapy. In addition, we recommend pasireotide LAR monotherapy in patients with headache not responsive to first-generation SRL therapy and in patients who experience side effects or are intolerant to PEGV monotherapy. In contrast to the current consensus criteria, we recommend considering combination therapy with pasireotide LAR and PEGV as third-line treatment in patients without diabetes at low PEGV dosages (≤80 mg/week) and in patients with tumor growth or symptoms of active acromegaly during first-generation SRL and PEGV combination therapy. With respect to pasireotide-induced hyperglycemia, we recommend a more liberal strategy of blood glucose monitoring during pasireotide treatment.

CONCLUSIONS

In contrast to the current consensus criteria, we recommend a more reluctant use of pasireotide LAR therapy for the treatment of acromegaly.

Absorption, distribution, metabolism and excretion of an isocitrate dehydrogenase-2 inhibitor enasidenib in rats and humans

1. The absorption, distribution, metabolism and excretion of enasidenib were studied following a single oral dose of [¹⁴C]enasidenib to rats (10 mg/kg; 100 μCi/kg) and healthy volunteers (100 mg; 318 nCi). 2. Enasidenib was readily absorbed, extensively metabolized and primarily eliminated via the hepatobiliary pathway. Enasidenib-derived radioactivity was widely distributed in rats. Excretion of radioactivity was approximately 95-99% of the dose from rats in 168 h post-dose and 82.4% from human volunteers in 504 h post-dose. In rat bile, approximately 35-42% of the administered dose was recovered, with less than 5% of the dose excreted as the parent drug. Renal elimination was a minor pathway, with <12% of the dose excreted in rat urine and <10% of the dose excreted in human urine. 3. Enasidenib was the prominent radioactive component in rat and human systemic circulation. Enasidenib was extensively metabolized in rats and human volunteers through N-dealkylation, oxidation, direct glucuronidation and combinations of these pathways. Glucuronidation was the major metabolic pathway in rats while N-dealkylation was the prominent metabolic pathway in human volunteers. All human metabolites were detected in rats.

Osilodrostat (LCI699), a potent 11β-hydroxylase inhibitor, administered in combination with the multireceptor-targeted somatostatin analog pasireotide: A 13-week study in rats

The somatostatin analog pasireotide and the 11β-hydroxylase inhibitor osilodrostat (LCI699) reduce cortisol levels by distinct mechanisms of action. There exists a scientific rationale to investigate the clinical efficacy of these two agents in combination. This manuscript reports the results of a toxicology study in rats, evaluating different doses of osilodrostat and pasireotide alone and in combination. Sixty male and 60 female rats were randomized into single-sex groups to receive daily doses of pasireotide (0.3mg/kg/day, subcutaneously), osilodrostat (20mg/kg/day, orally), osilodrostat/pasireotide in combination (low dose, 1.5/0.03mg/kg/day; mid-dose, 5/0.1mg/kg/day; or high dose, 20/0.3mg/kg/day), or vehicle for 13weeks. Mean body-weight gains from baseline to Week 13 were significantly lower in the pasireotide-alone and combined-treatment groups compared to controls, and were significantly higher in female rats receiving osilodrostat monotherapy. Osilodrostat and pasireotide monotherapies were associated with significant changes in the histology and mean weights of the pituitary and adrenal glands, liver, and ovary/oviduct. Osilodrostat alone was associated with adrenocortical hypertrophy and hepatocellular hypertrophy. In combination, osilodrostat/pasireotide did not exacerbate any target organ changes and ameliorated the liver and adrenal gland changes observed with monotherapy. Cmax and AUC0-24h of osilodrostat and pasireotide increased in an approximately dose-proportional manner. In conclusion, the pasireotide and osilodrostat combination did not exacerbate changes in target organ weight or toxicity compared with either monotherapy, and had an acceptable safety profile; addition of pasireotide to the osilodrostat regimen may attenuate potential adrenal gland hyperactivation and hepatocellular hypertrophy, which are potential side effects of osilodrostat monotherapy.

Effect of verapamil on the pharmacokinetics of pasireotide in healthy volunteers

We evaluated the drug-drug interaction between pasireotide SC and verapamil, a known P-glycoprotein inhibitor. Subjects received pasireotide SC (single dose, 600 μg) on day 1, and samples for pharmacokinetics evaluation were collected from days 1 to 8. Subjects received an oral dose of verapamil 240 mg/d for 10 days (days 15-24). On day 18, subjects also received pasireotide SC 600 μg. Pharmacokinetic sampling for pasireotide SC and verapamil was done during days 18 to 25 and days 15 to 21, respectively. Safety evaluations were performed throughout the study period, including a 30-day post-treatment follow-up. Pharmacokinetic profiles of pasireotide SC alone and in combination with verapamil sustained-release (SR) were superimposable with the geometric mean ratios (90% confidence interval [CI]) of 0.98 (0.91-1.06) for C(max), 0.97 (0.90-1.04) for AUC(last), and 0.98 (0.92-1.05) for AUC(inf). Exploratory analyses showed a 17% (90% CI, 0.72-0.94) reduction in C(trough) and 31% (0.58-0.82) reduction in C(max) (8 hours post-dose) for verapamil SR with pasireotide SC versus verapamil alone. Pasireotide SC with or without verapamil was well tolerated. In conclusion, there was no change in the rate of pasireotide absorption and elimination or extent of exposure following concomitant administration with verapamil.